Living multiple lives does bring the benefit of more skills.
You would prob want to get a few lives under your belt before you try beat the game if its really that hard...
but considering the tittle the peaceful ending is probably going to be a bad end just to emotionally destroy you as a player...
For example if a war starts and suddenly all your past lives die, that would really suck.
Tho the fact the end screen does mention them living happily afterwards so....
Maybe there is a time skip ?